a) Field of the Invention
This invention relates to polymer-bonded functional agents, and more specifically to polymer-bonded functional agents with an antioxidant, an ultraviolet absorber, a light stabilizer, an infrared absorber and/or an antistatic agent contained therein as a functional agent in a bonded form. The present invention is also concerned with processes for the production of the polymer-bonded functional agents, polymer-bonded functional agent compositions, processing methods for improving functions, and articles or products with improved functions.
a) Description of the Related Art
Synthetic resins, natural resins and semisynthetic resins (hereafter simply called “resins”) are accompanied by a problem in that they undergo a thermal deterioration under heat upon molding, forming or the like, an oxidative deterioration by oxygen in air when used or stored over long time, or a reduction in elasticity, a reduction in tensile strength, a reduction in physical properties, such as development of cracks, a deterioration in electrical properties, coloration and/or the like due to embrittlement or the like under the action of sunlight, especially ultraviolet rays. Likewise, products which contain a resin as an essential component—such as coating materials, paints, offset inks, gravure inks, textile printing inks—also develop a quality deterioration such as a gloss reduction, crazing or cracking, or blister of resin coatings or discoloration or fading of a pigment.
To lessen the above-described problems, antioxidants, for example, hindered phenolic antioxidants, phosphorus-containing antioxidants, sulfur-containing antioxidants and the like have been used commonly for oxidative deteriorations of resins. To avoid discoloration, embrittlement or the like of resins by ultraviolet rays, gloss reductions, crazing or cracking or blister of resin paints, or discoloration or fading of dyes or pigments, on the other hand, ultraviolet absorbers, especially benzotriazole ultraviolet absorbers, triazine ultraviolet absorbers, salicylate ultraviolet absorbers, benzophenone ultraviolet absorbers and the like have been used, or light stabilizers such as those of the hindered amine type have been used in combination with the above-described antioxidants and/or ultraviolet absorbers. Further, antistatic agents have also been used to prevent electrification.
Use of functional additives (functional agents) such as the above-described antioxidants, ultraviolet absorbers, and light stabilizers, however, develops various inconvenience because they are generally compounds of low molecular weight. For example, a functional agent of relatively low boiling point or a sublimable functional agent undergoes evaporation, sublimation or the like when a resin is molded, formed or otherwise processed under heat or is cured under heat. When a resin product or resin coating is brought into contact with warm water or an aqueous, acidic or alkaline solution or an organic solvent such as an alcohol or oil, the functional agent in the resin product is extracted from the resin. As a consequence, it is impossible to allow the effect of the functional agent to last for long time.
When a functional agent is mixed with a resin, poor compatibility between the functional agent and the resin causes bleeding or blooming on a surface of a molded or otherwise formed product of the resin or on a surface of a coating on the product during its long-term use. A problem, therefore, arises in that the content of the functional agent becomes low or that in the case of an adhesive or printing ink containing the resin, adhesion or printability may be lowered or the functional agent bled out onto the surface may stain other product(s) and/or article(s). On the other hand, addition of a functional agent in a large amount to a resin causes a phase separation between the resin and the functional agent, leading to reductions in the transparency and mechanical strength of the resin. A limitation is therefore imposed on the amount of the functional agent to be added. There has hence been a demand for the elimination or lessening of these problems. Further, a functional agent is generally a low molecular compound so that, when the functional agent adheres to the human body, it may cause irritation to skin or mucosa depending upon its type. In addition, powdery functional agents include those requiring attention from the standpoint of safety and/or health, for example, to the production of dust.
Some attempts have, therefore, been made to prevent evaporation, leaching or the like of an ultraviolet absorber when the ultraviolet resin is added to a resin. According to these attempts, one or more (meth)acryloyl groups are introduced into the ultraviolet absorber, and the resulting (meth)acryloyl-containing ultraviolet absorber is copolymerized as a monomer with another monomer so that the ultraviolet absorber is provided with a high molecular weight. In general, however, it has been difficult to prevent gradual polymerization of these (meth)acryloyl groups during storage. There is also a practical problem. A copolymer, which is available as described above, is a copolymer with another vinyl monomer such as an acrylic compound, a methacrylic compound, styrene or vinyl acetate. A limitation is hence imposed on the range of applicable resins because, for example, the thus-copolymerized ultraviolet absorber may not have sufficient compatibility with certain kinds of principal resins, e.g., polyolefin resins such as polyethylene and polypropylene, various polyester resins, diverse polyamide resins, and various polycarbonate resins. As physical property improvers for a wide range of general-purpose resins, the above-described problems still remain unsolved.